Apparatus for inserting and removing specimens from high temperature vacuum furnaces

ABSTRACT

A high temperature vacuum furnace having secured to the port thereof apparatus for the insertion of specimens to be tested and removal thereof from the test zone of the furnace. The apparatus comprises a high speed gate valve for isolating the interior of the furnace from an air lock chamber on the opposite side of the gate valve. The air lock chamber is provided with valve ports connected to a vacuum source, a source of inert quenching gas, and the atmosphere, respectively. Removeably attached to the end of the air lock chamber away from the furnace is a cylindrical tube having disposed within it a rod carrying a specimen pan at the end towards the furnace and having mounted at its top end an annular magnet having a diameter slightly less than the interior diameter of the tube. The top end of the tube is closed by a removeable cap. Encircling the tube in the vicinity of the magnet is a carbon steel ring which when axially moved along the tube causes the magnet to follow it and thereby controls the position of the rod and specimen pan within the tube. In an alternative embodiment, the magnet is replaced by an iron slug which serves as an armature for the coil of the solenoid which replaces the carbon steel ring. The specimen is inserted in the furnace without cooling the furnace down or disturbing the vacuum by first removing the tube from the outer end of the air lock chamber, placing the material to be tested in the specimen pan, and replacing the tube on the outer end of the air lock chamber. The valve in the port connected to the source of the vacuum is then opened to bring the pressure in the air lock chamber to that of the furnace. The gate valve is then opened and the ring moved along the tube towards the furnace thereby moving the rod and specimen pan until the specimen pan is within the test zone of the furnace. After the completion of the test, the specimen pan is moved to the air lock chamber, the gate valve closed, the specimen cooled, and the chamber brought to atmospheric pressure. Optionally, the specimen may be quenched with inert gas.

United States Patent 1 1 Whitehead [111 3,817,084 [451 June 18, 1974 1APPARATUS FOR INSERTING AND REMOVING SPECIMENS FROM HIGH TEMPERATUREVACUUM FURNACES Charles W. Whitehead, Newport News, Va.

[75] Inventor:

[73] Assignee: The United States of America as represented by theAdministrator of the National Aeronautics and Space Administration,Washington. DC.

22 Filed: Nov. 17,1972 211 Appl. No.: 307,729

[52] U.S. Cl. 73/15 R, 13/31 [51] Int. Cl. GOln 25/00 [58] Field ofSearch..... 73/15 R, 19, 190 R, DIG. 5;

Primary Examiner-S. Clement Swisher Attorney, Agent, or Firm-Howard J.Osborn; Wallace J. Nelson; John R. Manning [57 ABSTRACT A hightemperature vacuum furnace having secured to the port thereof apparatusfor the insertion of specimens to be tested and removal thereof from thetest zone of the furnace. The apparatus comprises a high speed gatevalve for isolating the interior of the furnace from an air lock chamberon the opposite side of the gate valve. The air lock chamber is providedwith valve ports connected to a vacuum source, a source of inertquenching gas, and the atmosphere, respectively. Removeably attached tothe end of the air lock chamber away from the furnace is a cylindricaltube having disposed within it a 'rod carrying a specimen pan at the endtowards the furnace and having mounted at its top end an annular magnethaving a diameter slightly less than the interior diameter of the tube.The top end of the tube is closed by a removeable cap. Encircling thetube in the vicinity of the magnet is a carbon steel ring which whenaxially moved along the tube causes the magnet to follow it and therebycontrols the position of the rod and specimen pan within the tube.

In an alternative embodiment, the magnet is replaced by an iron slugwhich serves as an armature for the coil of the solenoid which replacesthe carbon steel ring. The specimen is inserted in the furnace withoutcooling the furnace down or disturbing the vacuum by first removing thetube from the outer end of the air lock chamber, placing the material tobe tested in the specimen pan, and replacing the tube on the outer endof the air lock chamber. The valve in the port connected to the sourceof the vacuum is then opened to bring the pressure in the air lockchamber to that of the furnace. The gate valve is then opened and thering moved along the tube towards the furnace thereby moving the rod andspecimen pan until the specimen pan is within the test zone of thefurnace. After the completion of the test, the specimen pan is moved tothe air lock chamber, the gate valve closed, the specimen cooled, andthe chamber brought to atmospheric pressure. Optionally, the specimenmay be quenched with inert gas.

12 Claims, 2 Drawing Figures APPARATUS FOR INSERTING AND REMOVINGSPECIMENS FROM HIGH TEMPERATURE VACUUM FURNACES ORIGIN OF THE INVENTIONThe invention described herein was made by an employee of the NationalAeronautics and Space Administration and may be manufactured and used byor for The Government of the United States for governmental purposeswithout the payment of any royalities thereon or therefor.

BACKGROUND OF THE INVENTION There presently is an expanding need foreconomical ways of testing materials in a vacuum at very hightemperatures. This type of testing has become particularly importantwith the advent of requirements for high temperatures materials for usein space vehicles and the like. Up tothe present time, the insertion andremoval of test specimens from high temperature vacuum furnaces, whichoperate at temperatures on the order of 3,600F and higher, has requiredextremely long cycling times. Quite often the time required to cool thefurnace down, remove the specimen from the furnace, replace it withanother specimen, and then bring the furnace up to test temperature andvacuum, required a period of five hours or more. Removal of the specimenrequired shutting down the furnace, bringing the furnace to atmosphericpressure, and then removing the specimen. Only then could anotherspecimen be inse'rted and the furnace reheated, and a vacuum drawnagain. As indicated, this was time consuming and consequently expensive.

The present invention is concerned with an easily operated air lockmechanism which permits specimens to be inserted and removed from hightemperature vacuum furnaces in a very short time, i.e., twenty minutesor less, without decreasing furnace temperature or degree of vacuum. Thepresent invention thus provides a great economical saving in theoperation of high temperature vacuum furnaces.

There is no prior art known to applicant-which provides apparatus forrapidly inserting and removing test specimens from high temperaturevacuum furnaces. US. Pat. No. 2,874,107 discloses a neutronic reactorhaving an attachment thereto for placing materials to be irradiated inthe reactor and for removing them from the reactor. It is extremelycomplex and unsuitable for utilization in high temperature vacuumfurnaces.

SUMMARY OF THE INVENTION According to the present invention, there isprovided an air lock mechanism which is attached to high temperaturevacuum furnaces which allows a test specimen to be removed from thefurnace and replaced by a succeeding specimen without lowering thetemperature of the furnace or disturbing the vacuum thereof within acycling time of approximatelytwenty minutes. The air lock mechanismincludes a high speed gate valve which is secured over the port of thefurnace by a simple adaptor fitting, an air lock chamber mounted on thegate valve on the side of the valve away from the furnace, and acylindrical tube removeably mounted on the outer end of the air lockchamber. The air lock chamber is provided with valved portscommunicating with a source of vacuum, a source of inert quenchinggases, and the atmoshpere, respectively. Disposed within the tube thatis mounted on the air lock chamber is a specimen pan secured to theinner end of a rod within the tube. The osition of the rod andconsequently the specimen pan within the tube is magnetically controlledthrough means of a ring or coil surrounding the outer diameter of thetube acting in cooperation with either a magnet or iron slug at theouter end of the rod. The other end of the tube is closed by aremoveable cap.

The specimen is inserted in the furnace by placing the specimen on thespecimen pan following removal of the tube from the outer end of the airlock chamber. The tube replaced on the outer end of the air lock chamberand the air lock chamber is brought to a vacuum equal to that within thefurnace. The gate valve is then opened, and through magnetic means, thespecimen pan is moved into the test zone of the furnace by moving therod inwardly in the tube. After completion of the test, the rod iswithdrawn outwardly until the specimen is within the air lock chamber,the gate valve closed, and the specimen cooled down with or withoutquenching in inert gases, and the air lock chamber brought toatmospheric pressure. The specimen is then removed by removing the tubefrom the outer end of the air lock chamber.

BRIEF DESCRIPTION OF THE DRAWING DESCRIPTION OF PREFERRED EMBODIMENTSReferring to FIG. 1 of the accompanying drawing, the apparatus of thepresent invention indicated generally at 2 is shown attached to a hightemperature vacuum furnace 4. The furnace 4 has, as shown by the dottedlines, a test heating zone 8 that is located in the center of thefurnace 4 which in the embodiment shown is cylindrical. Attached to thetop 7 of the furnace by means of an annular flange 10 secured to thefurnace 4 by bolts 12 is a hollow cylindrical adaptor 14, the top ofwhich is connected by way of flange 24 to a high speed gate valveindicated generally at 16. The adaptor l4 fits over port 13 of thefurnace 4 and is axially aligned therewith. The gate valve 16 may be onewhich is manually operated or preferably is a vacuum operated valve toassure high speed operation. Pneumatically or electrically operated gatevalves may also be utilized. The valve 16 has a cylindrical passage 18pass ing through the body of the valve which, when the valve 16 is inthe closed position, is closed by the gate 20 indicated schematically inthe drawing. In the drawing, the actuator of the valve 16, in this casethe handle, is indicated at 22. Secured to the top of the valve 16 bymeans of flange 26 having a central opening 27 and bolted to the body ofthe valve 16, is a hollow cylindrical air lock section or chamber 28.The cylindrical air lock chamber 28 which is preferably made of 347stainless steel is provided with valved ports 30, 32 and 34,respectively, communicating with the interior of the chamber 28.

The port 30 is in turn connected to a vacuum source,

not shown, the port 32 to a source of inert gas, not

shown, and the port 34 connects directly with the surroundingatmosphere. The top end of the chamber 28 is provided with an annularflange 36 having a central opening 37 therein. The flange 36 is in turnconnected to a similar annular flange 38 with opening 39 at the base ofthe hollow cylinder tube 42 by bolts 40. The flanges 36 and 38 aresealed along their interface 41.

As described in greater detail below, the bolts 40 may be removed andthe flanges 36 and 38 separated to provide for a removal of testedspecimens and insertion of new specimens.-

Disposed axially within the tube 42 is a rod 44 having a specimen pan 46connected to the bottom thereof. A magnet 48, just slightly less indiameter than the internal diameter of the tube 42, is secured to thetop or rod 44. Rod 44 and specimen pan 46 may be'constructed of anysuitable high temperature resistant material as will be furtherexplained hereinafter.

A carbon steel ring 58 having an internal diameter only slightly largerthan the external diameter of the tube 42 is utilized to control theaxial movement of the rod 44. Movement of the ring'58 along the tube isfollowed by the magnet 48 which in turn moves the lo 44 and pan 46 withthe specimen.

Attached to the upper end of the tube 42-is annular flange 50 having acentral opening 51 therein. An annular cap 52 is held in place on theannular flange 50 by means of studs 54. The interface of the flange 50and cap 52 is indicated at 56. v

Material to be tested is placed in the specimen pan 46 after the tube 42with rod 44 and pan 46'have been removed from the top of the air lockchamber 28 by unbolting and separating the flanges 36 and 38.

If desired, rather than separating flanges 36 and 38, the tube 42 withair chamber 28 attached to it can be removed from the top of the valve16 by unbolting flange 26. p

As previously indicated, the position of the rod 44 and consequently thespecimen pan 46-within the tube 42 is'controlled by moving the ring 58axially along the outside of the tube 42. This in turn moves the rod 44as the magnet 48 follows the movement of the ring 58.

After the specimen to be tested is placed in specimen pan 46, the tube42 is secured to the top of the air lock chamber 28 by bolting flanges38 and 36 together. The

gate valve 16 is in the closed position during the preceding operation.A vacuum is drawn on the air lock section 28 by opening the valve of theport 30 thus placing the air lock chamber in communication with thevacuum source. When the pressure in the air locks equal that in thefurnace, the gate valve 16 is opened, the ring 58 is moved axiallydownwards with the magnet 48 at the top of the rod 44 following untilspecimen pan 46 arrives within the test zone 8.

Following the test period, the specimen on pan 46 is removed from theheat zone 8 by moving the ring 58 axially along tube 42 away from thefurnace, thus moving the magnet 48 and consequently the rod 44 with thespecimen pan 46 upward out of the furnace 4. When the pan 46 is withinthe air lock section 48, the movement of the ring 58 is stopped, thegate valve 16 closed, and the air lock chamber 28 either brought toatmospheric pressure and the specimen allowed to cool, or

if desired, the specimen may be quenched with a flow of inert gas suchas helium or argon by opening the valve air port 32 and pumping in thequenching gas. The valve of port 30 is closed at this time.

If desired, the cap 52 can be unbolted so the cap 52 can raise slightlyand allow the excess gas pressure to vent at the interface 56 of the cap52 and flange 50.

As is apparent, the apparatus of this invention permits the removal ofthe test specimen from the furnace without loss of pressure in thefurnace or lowering of the temperature of the furnace. Another testspecimen readily can be placed in the furnace by repeating the sameprocedure after removing the cooled specimen from the air lock chamber.This cycling can be com pleted in most cases within twenty'minutes orless.

In FIG. 2 is shown an alternative embodiment ofthe mechanism for movingthe rod holding the specimen terface of the cap 152 and flange 150 isindicated. at

156. In this embodiment, the magnet at the top of the rodis replaced byan annular iron slug 148 to which the rod 146 is fixed. The iron slug148 serves in effect as the armature for the solenoid, the coil windingsof which are indicated at 158 and encircle the tube 142. The solenoid158 is connected to a power source not indicated by conduit 160. Theposition of the specimen pan 146 is thus controlled by moving thesolenoid coil 158 along the tube 142, which in turn causes the armature148 of the solenoid to move the rod 144 within the tube 142 therebycontrolling the position of the specimen pan 146.

The specimen pan and'rod should be constructedof high temperatureresistant'materials such as tantalum, tungsten, molybdenum, graphite, orceramic. The remaining parts are generally constructed of stainlesssteel. The tube 42 alternatively may be constructed of clear'quartz sothat the position of the rod and specimencan be followed visually.

The present invention thus provides apparatus which allows testspecimens to be inserted into and removed from a high temperature vacuumfurnace easily and rapidly without interrupting the continuous operationof the furnace. Whereas cooling the furnace and the removal of a testedspecimen and insertion of a new specimen into the furnace and returningthe furnace to test conditions often required five or more hours toaccomplish previously, with the apparatus of this invention, the cyclingcan often be completed in twenty minutes or less.

While the invention has been explained by detaileddescription of certainspecific embodiments, it is understood that various modifications andsubstitutions can be made in any of them within the scope of theappended claims which are intended also to include equivalents of suchembodiments.

What is claimed is: v

1. Apparatus for placing a specimen in a high temperature vacuum furnaceand removing said specimen therefrom without disturbing the temperatureor vacuum of said furnace, said furnace having a port communicating witha test zone in said furnace, said apparatus comprising adaptor'meansconnecting a first side of a gate valve means to said port in saidfurnace, a second and opposite side of said gate valve means connectedto a first side of an air lock chamber, valved means associated withsaid air lock chamber for selectively placing said chamber incommunication with a vacuum source, further valved means associated withsaid air lock chamber for selectively placing said chamber incommunication with the atmosphere, an elongated hollow cylinder tubeconnected to the second and opposite side of said air lock chamber,specimen holder means movable by means operative from outside of saidhollow cylinder tube through said air lock chamber. and said gate valvemeans when opened, and to and from said test zone, said specimen holdermeans including an elongated rod having a specimen pan secured to oneend thereof and a magnet secured to the opposite end thereof and saidmeans operative from outside of said hollow cylinder tube consists of acarbon steel ring slidably disposed thereon.

2. Apparatus as claimed in claim 1 wherein said gate valve means is avacuum operated gate valve.

3. Apparatus asclaimed in claim 1 wherein said air lock chamber includesadditional valved means for placing said chamber in selectivecommunication with a source of inert gas.

4. Apparatus for placing a specimen in a high temperature vacuum furnaceand removing said specimen therefrom without disturbing the temperatureor vacuum of said furnace, said furnace having a port communicating witha test zone in said furnace, said apparatus comprising adaptor meansconnecting a first side of a gate valve means to said port in saidfurnace, a second and opposite side of said valve means connected to afirst side of an air lock chamber, valved means associated with said airlock chamber for placing said chamber in communication with a vacuumsource, further valved means associated with said air lock chamber forplacing said chamber in communication with the atmosphere, a hollow tubeconnected to the second and opposite side of said lock chamber, theinterior of said tube being in communication with the interior of saidair lock chamber, a rod disposed longitudinally within said tube, aspecimen holder removeably attached to a first end of said rod, saidfirst end being the end of said rod disposed towards the furnace, a capclosing the second end of said tube, and magnetic means for moving saidrod axially within said tube, said magnetic means comprising ring meansencircling said tube exteriorly thereof in the vicinity of a cooperativemeans secured to the second end of said rod, the axial movement of saidring means causing the axial movement of said rod within said tube dueto magnetic forces to thereby move said specimen holder through said airlock chamber and through said gate valve 8. Apparatus as claimed inclaim 4 wherein said gate valve'means comprises a manually operated gatevalve.

9. Apparatus as claimed in claim 4 wherein said gate valve meanscomprises a pneumatically operated gate valve.

10. Apparatus as claimed in claim 4 wherein said gate valve meanscomprises an electrically operated gate valve.

11. Apparatus as claimed in claim 7 wherein said air lock chamberincludes valved means for placing said chamber in communication with asource of inert gas.

12. Apparatus comprising adaptor means suitable for connecting a firstside of a vacuum operated gate valve to a port of a high temperaturevacuum furnace having a test zone therein, a second and opposite side ofsaid gate valve connected to a first side of an air lock chamber, firstvalved means associated with said air lock chamber for placing saidchamber in communication with a vacuum source, second valved meansassociated with said air lock chamber for placing said chamber incommunication with the atmosphere, and third valved means associatedwith said air lock chamber for placing said chamber in communicationwith a source of inert gas, a hollow tube connected to the second andopposite side of said air lock chamber, the interior of said tube beingin communication with the interior of said air lock chamber, a roddisposed longitudinally within said tube, a specimen holder removablyattached to a first end of said rod, said first end being the end ofsaid rod disposed towards said furnace, a cap closing the second end ofsaid tube, magnetic means for moving said rod axially within said tube,said magnetic means comprising a solenoid coil encircling said tubeexteriorly thereof in the vicinity of an iron slug secured to the secondend of said rod, the axial movement of said solenoid coil causing theaxial movement of said rod within said tube to thereby move saidspecimen holder through said air lock chamber and through said gatevalve when opened, and to and from said test zone.

1. Apparatus for placing a specimen in a high temperature vacuum furnaceand removing said specimen therefrom without disturbing the temperatureor vacuum of said furnace, said furnace having a port communicating witha test zone in said furnace, said apparatus comprising adaptor meansconnecting a first side of a gate valve means to said port in saidfurnace, a second and opposite side of said gate valve means connectedto a first side of an air lock chamber, valved means associateD withsaid air lock chamber for selectively placing said chamber incommunication with a vacuum source, further valved means associated withsaid air lock chamber for selectively placing said chamber incommunication with the atmosphere, an elongated hollow cylinder tubeconnected to the second and opposite side of said air lock chamber,specimen holder means movable by means operative from outside of saidhollow cylinder tube through said air lock chamber and said gate valvemeans when opened, and to and from said test zone, said specimen holdermeans including an elongated rod having a specimen pan secured to oneend thereof and a magnet secured to the opposite end thereof and saidmeans operative from outside of said hollow cylinder tube consists of acarbon steel ring slidably disposed thereon.
 2. Apparatus as claimed inclaim 1 wherein said gate valve means is a vacuum operated gate valve.3. Apparatus as claimed in claim 1 wherein said air lock chamberincludes additional valved means for placing said chamber in selectivecommunication with a source of inert gas.
 4. Apparatus for placing aspecimen in a high temperature vacuum furnace and removing said specimentherefrom without disturbing the temperature or vacuum of said furnace,said furnace having a port communicating with a test zone in saidfurnace, said apparatus comprising adaptor means connecting a first sideof a gate valve means to said port in said furnace, a second andopposite side of said valve means connected to a first side of an airlock chamber, valved means associated with said air lock chamber forplacing said chamber in communication with a vacuum source, furthervalved means associated with said air lock chamber for placing saidchamber in communication with the atmosphere, a hollow tube connected tothe second and opposite side of said lock chamber, the interior of saidtube being in communication with the interior of said air lock chamber,a rod disposed longitudinally within said tube, a specimen holderremoveably attached to a first end of said rod, said first end being theend of said rod disposed towards the furnace, a cap closing the secondend of said tube, and magnetic means for moving said rod axially withinsaid tube, said magnetic means comprising ring means encircling saidtube exteriorly thereof in the vicinity of a cooperative means securedto the second end of said rod, the axial movement of said ring meanscausing the axial movement of said rod within said tube due to magneticforces to thereby move said specimen holder through said air lockchamber and through said gate valve means when opened, and to and fromsaid test zone.
 5. Apparatus as claimed in claim 4, wherein ring meanscomprises a carbon steel ring and said cooperative means comprises amagnet.
 6. Apparatus as claimed in claim 4 wherein said ring meanscomprises a solenoid coil and said cooperative means comprises an ironslug which acts as the armature for said solenoid coil.
 7. Apparatus asclaimed in claim 4 wherein said gate valve means comprises a vacuumoperated gate valve.
 8. Apparatus as claimed in claim 4 wherein saidgate valve means comprises a manually operated gate valve.
 9. Apparatusas claimed in claim 4 wherein said gate valve means comprises apneumatically operated gate valve.
 10. Apparatus as claimed in claim 4wherein said gate valve means comprises an electrically operated gatevalve.
 11. Apparatus as claimed in claim 7 wherein said air lock chamberincludes valved means for placing said chamber in communication with asource of inert gas.
 12. Apparatus comprising adaptor means suitable forconnecting a first side of a vacuum operated gate valve to a port of ahigh temperature vacuum furnace having a test zone therein, a second andopposite side of said gate valve connected to a first side of an airlock chamber, first valved means associated with said air lock chamberfor placing said chamber in communication with a vacuum source, secondvalved means associated with saiD air lock chamber for placing saidchamber in communication with the atmosphere, and third valved meansassociated with said air lock chamber for placing said chamber incommunication with a source of inert gas, a hollow tube connected to thesecond and opposite side of said air lock chamber, the interior of saidtube being in communication with the interior of said air lock chamber,a rod disposed longitudinally within said tube, a specimen holderremovably attached to a first end of said rod, said first end being theend of said rod disposed towards said furnace, a cap closing the secondend of said tube, magnetic means for moving said rod axially within saidtube, said magnetic means comprising a solenoid coil encircling saidtube exteriorly thereof in the vicinity of an iron slug secured to thesecond end of said rod, the axial movement of said solenoid coil causingthe axial movement of said rod within said tube to thereby move saidspecimen holder through said air lock chamber and through said gatevalve when opened, and to and from said test zone.